Vector Blur mucking up transparency

starbase1

May the sauce be with you
Hi All,
I'm getting myself in a mess with a scene which I am making using layers exported as PNG-32 for assembly in a video editing prog.

I thought I had worked my way through how transparency is handled differently in the save, (for example, how a bright highlight on glass fades out when that image is saved with transparency if there's nothing behind it).

Now I'm getting in a mess with applying some blur to the scene. It's probably the most complex scene I've done, it's 4k, and render times are high, so I'm trying to avoid using full motion blur.

But vector blur is darkening transparent surfaces, and I have no idea why! I can actually watch in happen in the render preview!
I attach 3 different renders. The Earth in the background is composited in as a background image in Lightwave.

So...

Is there a work around so I can use vector blur? Or do I need to bite the bullet and accept very high render times?

Clues for the clueless gratefully received!
Nick
blur-effectsr.jpg
 

kadri

Member
I haven't used vector blur. But i would try it with the background image on a plane object and see if it is the same.
 

RPSchmidt

Active member
I could be wrong, but I don't think there is any way around the vector blur issue. If I'm remembering correctly, vector blur has always had issues with transparency.

If you are rendering for animation and exporting PNGs to an editing program and high render times are a concern, I personally recommend applying motion blur in your editing program in post.

80-90% of the time when I am rendering for compositing or animation, I apply motion blur in post. It's not as precise, but the difference isn't really noticeable to the viewer and I have greater control over the amount of blur and its area of effect.

If you need the higher precision of in-render motion blur, then with LW's native renderer, I guess you are stuck.
 

starbase1

May the sauce be with you
I could be wrong, but I don't think there is any way around the vector blur issue. If I'm remembering correctly, vector blur has always had issues with transparency.

If you are rendering for animation and exporting PNGs to an editing program and high render times are a concern, I personally recommend applying motion blur in your editing program in post.

80-90% of the time when I am rendering for compositing or animation, I apply motion blur in post. It's not as precise, but the difference isn't really noticeable to the viewer and I have greater control over the amount of blur and its area of effect.

If you need the higher precision of in-render motion blur, then with LW's native renderer, I guess you are stuck.

Thanks for that, I feared as much...
I have no idea how to add vector blur in post! Any clues please?

Nick
 

RPSchmidt

Active member
Thanks for that, I feared as much...
I have no idea how to add vector blur in post! Any clues please?

Nick

So for compositing in post, vector motion blur and standard pixel motion blur are two very different beasts.

Most compositing software comes with some type of standard pixel motion blur. The method for vector motion blur will depend on what compositing software you are using (After Effects, Nuke, Fusion, etc).

Vector motion blur has to be exported out as a separate pass. Then, if your compositing software includes a native method to use that motion vector pass, it should be relatively easy.

Standard pixel motion blur relies on the perceived motion of the pixels in a given image and is applied to an entire frame. It is less precise, but if you composite for it, it can be extremely useful and very fast.

Here are some great posts that are chock-full of information on the use of vector motion blur.

http://forums.newtek.com/showthread.php?t=108711

https://forums.newtek.com/threads/lightwave-and-motion-vectors.125432/post-1214735

As you can see, you may have to purchase at least one plug-in, depending on the method you use.

Good luck!
 

starbase1

May the sauce be with you
So for compositing in post, vector motion blur and standard pixel motion blur are two very different beasts.

Most compositing software comes with some type of standard pixel motion blur. The method for vector motion blur will depend on what compositing software you are using (After Effects, Nuke, Fusion, etc).

Vector motion blur has to be exported out as a separate pass. Then, if your compositing software includes a native method to use that motion vector pass, it should be relatively easy.

Standard pixel motion blur relies on the perceived motion of the pixels in a given image and is applied to an entire frame. It is less precise, but if you composite for it, it can be extremely useful and very fast.

Here are some great posts that are chock-full of information on the use of vector motion blur.

http://forums.newtek.com/showthread.php?t=108711

https://forums.newtek.com/threads/lightwave-and-motion-vectors.125432/post-1214735

As you can see, you may have to purchase at least one plug-in, depending on the method you use.

Good luck!
Thanks!
I think for this project I will just bite the bullet and accept the rendering overhead, but it's good to know the options.
Nick
 

kadri

Member
Hmm...that is the reason i don't like forums as in the past.
I would at least say something like thanks and say something like "i tried it" etc...

I don't know how you setup your scene so it might work or not.
But in my test using a background image in the compositing tab and using a plane with front projection got different results.

This is the first time i tried vector blur and just throw this together in 10 minutes so it looks crude...
 

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